The present invention relates to bench drill grinding machines of small size, and more specifically to a drill grinding machine which can be used in various machine manufacturing fields such as industrial machine manufacturing, welfare machine manufacturing, household electric machine manufacturing, electric machine manufacturing, automobile manufacturing, building material manufacturing and the like.
As an example of such small-sized drill grinding machine in the prior art, a drill grinding machine disclosed in Japanese utility model application (publication No. 53-47) is known.
The drill grinding machine comprises
(a) a casing;
(b) a turn table having a drill attaching hole at the center and supported by the casing and rotatable around a first axial center passing through the drill attaching hole;
(c) a table drive device for driving the turntable to rotate;
(d) a chuck device having pawls provided at the center of the turn table and movable perpendicularly direction to the first axial center, for grasping the drill using the pawl so that the axial center of the drill coincides with the first axial center;
(e) a grinding wheel being rotatable in parallel to the first axial center that is and around a second axial center shifted in the perpendicular direction to the first axial center, for grinding a cutting edge at the top end of the drill rotating together with the turn table;
(f) a grinding wheel drive device for driving the grinding wheel to rotate;
(g) a grinding wheel support device provided with a first support member to rotatably support the grinding wheel, a second support member to support the first support member and being movable relative to said first support member in the extending direction of (parallel to) the second axial center; and a third support member to support the second support member and being movable relative to said second support member perpendicularly to the second axial center, for supporting the grinding wheel, the grinding wheel being accordingly movable perpendicularly to a direction parallel to the drill axial center;
(h) a grinding wheel drive lever installed near the grinding wheel support device and being rotatable around a third axial center that is perpendicular to the second axial center a one end thereof being engaged with the second support member, and threaded end -O- having a threaded portion;
(i) a first transmission shaft threadedly engaged with the threaded portion of the grinding wheel drive lever;
(j) a second transmission shaft connected to the first transmission shaft so that it cannot be rotated relative to said first transmission shaft but can be moved relative to said first transmission shaft in the axial direction thereof;
(k) first and second cams installed on outer circumferential part of the turntable;
(l) a first grinding wheel moving mechanism having a first follower to follow the first cam, for converting the movement of the first follower into movement of the first transmission shaft in its axial direction, for rotating the grinding wheel drive lever, and for accordingly moving the grinding wheel forward and backward in the drill axial direction as a result of contact of said one end of the lever with the second support member; and
(m) a second grinding wheel moving mechanism having a second follower to follow the second cam, for converting the movement of the second follower into movement of the second support member perpendicularly to the second axial center, is that the grinding wheel is moved forward and backward perpendicularly to the drill axial center.
In the drill grinding machine, if the drill to be re-ground is grasped by the chuck device and the turntable and the grinding wheel are driven to rotate, the grinding wheel is reciprocated in the drill axial direction and perpendicularly thereto according to a definite locus specified by the contours of the first and second cams during each revolution of the drill and turn table, and thereby the re-grinding and the thinning of the drill cutting edge are performed simultaneously.
However, in the drill grinding machine, the grinding wheel is returned to the initial position after one revolution of the drill and the turntable. Consequently, in order to perform the infeed of the drill cutting edge more deeply, the position of the grinding wheel must be displaced by adjustment of its infeed, for example, by rotating an operation handle of a grinding wheel displacement device to displace the position of the grinding wheel in parallel to the drill axial center. Accordingly, the drill grinding machine has problems in that the grinding work is not so easy.